Improvement in projectiles for rifled ordnance



B. s. ROBERTS.

Projectile.

' Patented Marj24, 1863.

- To a, whom it may concern.-

.nnxmurx s. non ni rs', or THE iixlrni fsrlxrrlsAnny; .f

y im tates ENI'T m; P- oe l-ICTI LES FOR 1 FLE'DLO Romance.

Specification forming. part of Letters Patent No. 37,929, datedifila Be it known thatI, BENJAMIN S. ltoincn'rs,

I of the United States Army, have invented a new and improved mode of constructing shot 1 and. .shelltwhieh are intended to be thrown frontrifled-cannon.; and I do hereby declare .thatthe followiug isa mama exact descripation thereof, which will be more fully understood hyrreference to the accompanying draw- ",i gs, h ch? *Figure' l rep resents the body of theshot or 1 shell, Fig. 2 is a section of the shell when com- I plete Fig. 13 is a section ofthe shell along the lineww-ofFigl FigAisa longitudinal section Y, of acuporband of soft metal which is to fit onto the rear portion of the projectile. Fig. 5 is a" lllodifiQit-t-ipll of the projectile;

filled with a lubrieat n the shot having been .i construe ted and placed in'a propermold; the sottnie-tal "may be castnpon. the shot" at once; lirrr-ear' of the shoulder and in front o'fthe cup orhandi 'leave a. I smell ring or spaee,extending entirely around the projectile; or, instead of a continuous ring,

independent recesses o f a semicircular or other form may be constructed, as'sliown'iirFig, 1. This ring or, these re es' aireintendetlto be .O' to the fi "no; of the proiectile. 5 They alsoleave room for the cupor a dciojbe p'i opciled for ward, in order tha maybe niorereadily and uniformly expandeghseasto fill thegrooves of the CitllllOlL' lhisyup ornband;may be shaped as in Fig, ,5, entirely ClOSBflfill the rear; but I prefer leaving it open at the, bot- 1 compound previous q My inventioneonsists in ashot or s'hellmade tom, as shown in Fig. 2, and even itthe outer lof two principal parts, thc 'front andeentral angles at'the rear end, f flare cut'oti, as shown portion constituting the chief bulk of the pro v in Fig. 2 in red lines, theietiectiweiressgofi the jectile' being composed of cast-iron,'and the L "rear portion ofithe projectile is surrounded by acupor band of soft metahwhioh is intended to constitute a part of the projectile and to fly wane. This cup-or band may be composed of any metal of thedproper degree'of hardness and tenacity but I prefer making it of lead, or some of the compounds of whichthat metal constitutesoneoftlieingredients: xl.he"point, or forward end ofgthe projectile may heniade' in any of the usual; shapes. A little forward j: of the center of gravity of the whole shot (in- "ame ter ofthe same, thus leaving a suitable space for the reception of the soft-metal cup or hand. This rear portion of the cast irou part of the shot I call'the spindle. It may be made in the form of a cone, or of the frus-' tum of a cone, or in various other-shapes; but for-reasons hereinaftergiven, Iprefer giving it the shape of aparaboloid and ot'afrusturn thereof. Upon this spindle I form tongues or lands, which are made to fit into grooves cast upon the interior surface of the cup or 'soft-metal band, in order that the soft nietal may have so firm a grip upon 'tliedna'in portion of the projectile that when rotation isgiven to the former it will he sure to carry the latter with it. The soft-metal cup-m band may be cast separately and afterward driven ou upon the cast; ir n spindle or' ihe body ot' thus prepared, is qiic iusertedinto the niuzzlc of the gun'and rammed hon e intheQusual way. The explosion otl the powiderforees the soft metal forwardupou the 1 at ccausing itfto expand, so as entirely.tofhii, the bore-0t" the cannon and prevent windage.

ltis a well-knowirpropertyg'ef that the abseis'sas are propo squares of the ordinates' Byni'; die of the form of a parabol oid circles formed by sections of thi perpendicular to its this will be iii: ect proportion totheir respective distancesirom the apex of the parabol'oid, inasmuch as" these cir cles are in direct proportion to the squares of their radii-that is to say, they are, in direct proportion to their respective distances from the apex of the paraboioid. "In such cases, therefore, this band of .sot't: metal, if driven di reetly forward,will'swell equally atall points of its length, so as to. take the sanie'hold of the'grooves of theeannou at all those points. This effect inay 'be produced sutiieiently'lbr all practical purpose without'n aking the spindie an exact parahoioid; It will beLsutiicient it it has a curved surface nearly approximating that formythe enormous pressure ofthe liberated gases being sufficient to overcome any defects in theshapc of the spindle inthis ng the spineretore, the nraboloid particular; but I prefer making the convex i parabola t to the surface of the tongues or lands of the spindle of the form of one paraboloid, and the -co nvex surface of the bottom of the grooves on thespindle of another paraboloid having a common apex, in which case the expansion of the soft metal will be exactly equal throughout its entire length.

I make the entire projectile, including the soft metal, of such proportions that the center of gravity will fall in rear of the shoulders g 9, so that the projectile may have a longer bearing in the gun, and, taken in connection with the shape and proportions of the parts in other respects, will. cause it to flysteadily without any danger of tumbling, and without any serious exhibition of what is termed nutation in itsfiight.

I sometimes form a ring-shaped concavity, c e, around the whole circumference of the rear end of the shot in the soft-metal band,

by which means a rim will be provided which .will'be forced into the grooves of the cannon on the same principle as that which'gives the Minie ball its distinguishing property.

iTheI shoulders g 9, instead ofbein'g constructed at right angles to the axes of the shot, may be made with an .acute angle, having its point forward, by which means the-softmetal bandwill he stayed and supported by these acute-angled shoulders. e

I am aware that projectiles have been constructed having their main body composed of cast-iron with a-band of soft metal attached to the rear end of such body, and so contrived that the expansive force of the gases resulting'from the explosion of the powder, acting from within or underneath this soft inetal, should force it outward into the grooves of the cannon to communicate a rotary motion to such projectile. This plan is objectionable principally for the reason that it does not hold the projectile firmly in the axis of the cannon, by which means a wabbling motion is communicated to it. l

I am also aware-that projectiles have-been constructed having a main body of cast-iron surrounded by a band of soft metal or its equivalent, which was followed up by a ring or cup of cast-iron, by means of which the.

soft metal would, upon thedischarge of the 5 canuombe pressed between two shoulders of iron, and thus forced out into the grooves of the cannon, This arrangement'is liable to the objection that it is composed of too many parts, and thering or cup which is made to follow up the band of soft metal is liable to be broken or to fly from the base of the jcetile',

I am likewise'aware thatva band or sabot of soft metal has been contrived by \V-illiani E. \Voodbridge, embracing the rear end of a castiron shot, and extendingforwand so as measurably tocmbrace the center of gravity of the projectile; but as its exterior surface is left s|nooth, without shoulder or grooves, the soft sabot will have nothing againstwhich to abut,

in order to be forced into the grooves of the "gun; and, even if that objection did not exist,

the absence of grooves or their equivalent would leave the sabot without a suflicient hold upon the shot to insure its being rotated by the rotation of the sabot.

Finally, I am aware that, in 1861, John A.

Dahlgren obtained a patent for a shot composed of a cast-iron body, having its rear end inclosed by a soft-metal cup, having also a shoulder to abut against, -and longitudinal tongues fitted to grooves in the soft-metal cup, in order to insure rotation in the hard-metal body whenever the soft-metal cup was made to rotate; but'this soft metal of Dalhgren was only intended'to embrace the base of the body of the shot. He had never contemplated such, a contrivance as should prevent thehard castiron portion of the projectile from being brought into violent collision with the internal surface of the bore of the gu n. On the contrary, he constructed longitudinal ribs upon the exterior surface of his shot to diminish'the friction-by diminishing the extent of the surface that should actually be brought in contact with the surface of the bore-ofthe;gun,where as by my arrangement the axis of the project ile is held steadilyin the axis of the gun, and

the hard-metal body .of that projectile is kept entirely out of contact withthe: metal of the gun, by which means cannonimade of brass or other soft metal can be safely used, ,which can never be the case with the Dahlgren shot. a

' \Vhat, therefore, I claim as new, and desire to secure by Letters Patent, is;-

1. In a projectile forrified ordnance composed of a body of cast-iron'and a cup or band of soft metal, and having upon its body a shoulder running transversely around the same, and a spindle furnished with longitudinal tongues and grooves,'constructing the projectile of such proportions that the soft metal shall so embrace the center of gravityof the entire projectile as-to furnish a bearing for. the same while passing through the cannon, substantially in-the manner and for the purpose above described. v

2. In a projectile constructed as described in the preceding claim, forming the surface of the spindlein the shape of a paraboloid, or such an approximation thereto that the soft metal may, by the force of the explosion, be crowded uniformly outward on all sides and at all parts of its length,whereby the axis of the projectile may be placed and held firmly in the axis of the cannon while passing through the same, thereby securing a steady motion of rotation to the shot throughout its flight,

substantially as and for the purpose above described.

Witness my hand and seal, in the matter of myapplioation for a patent for improved shot andshell, this 22d day of December, A. D.

B. s. nonnn'rs. n a] '\\''iincsses: A,

G'c'srnvr. DrE'rRrcn,

EDM. F. BROWN, 

